VAnet2 - GENESIS implementation of the Vogels-Abbott model

This is a GENESIS re-implementation of the Vogels and Abbott (2005)
model that was used as a benchmark for network simulators in the
review by Brette et al. (2007). It has single compartment neurons
with Hodgkin-Huxley dynamics and dual exponential synaptic
conductances, rather than the usual integrate and fire models.

Model Description

This version serves as a tutorial on the use of hsolve with network
models in order to achieve speedups by a factor of 10 to 20. The
'VAnet2-batch.g' script is intended to be extended for testing GENESIS
spike timing dependent plasticity (STDP) implementations with
hsolve. This script would be a good starting point for models that use
more realistic cells and connections.